Dead student's family call for clampdown on slimming drugSarah Houston, 23, died after taking banned dinitrophenol (DNP), which she ordered online, alongside antidepressants

Sarah Houston was studying medicine at the University of Leeds at the time of her death last September. Photograph: Christopher Thomond

A coroner and the family of a medical student suffering from bulimia who died after taking a banned weight-loss drug bought online have called for a change in the law to further tighten the distribution of the substance, which has been blamed for other deaths.

Dr Graham Mould, a forensic toxicologist, told an inquest into the death of Sarah Houston, 23, that a combination of dinitrophenol (DNP), which is banned from human consumption but is used as a chemical pesticide, and antidepressants may have been fatal.

DNP, which was first used to treat obesity in the 1930s but was banned as a food substance due to its dangerous side effects, continues to be used as a slimming aid by bodybuilders around the world. It was linked to 62 deaths in a study published last year in the Journal of Medical Toxicity.

The University of Leeds medical student, who comes from a family of doctors, is believed to have been taking the drug secretly alongside a prescribed antidepressant Fluoxetine. Houston was found dead in her bedroom by a flatmate.

The inquest in Wakefield heard she had complained of feeling hot and unwell and had been breathing heavily on the evening before she died in September last year.

Mould said there was no evidence of an overdose. "We don't know how long Sarah had been taking DNP but it may have accumulated in her system," he said. "It increases the body's metabolic rate. The side effects can be overheating and breathlessness caused by an increased heart rate and this seems to be consistent with how Sarah was feeling that evening.

"The side effects of DNP were clearly present and it's possible that Fluoxetine may have exacerbated the affect of DNP. At a very high dose, Fluoxetine can have a similar affect to DNP and so one can speculate that the two drugs together might have speeded up the affect."

Mould pointed out that the Food Standards Agency had previously issued a report warning the public not to take DNP.

Coroner David Hinchliff said: "The only way to combat the use of DNP is to bring to the attention of the public how dangerous a substance it is.

"This is not a one-off case and it needs bringing to the public's attention."

Outside court, Houston's family said she was not depressed at the time she died and her health had improved leading up to her death. In a statement, they said that it was incomprehensible that DNP could be purchased over the internet and called on the government to take steps to ensure that no other family suffered in the same way in future.

"It's going to be a slow process, but hopefully approaching the Home Office to begin with will be the right step and hopefully it will be made illegal," said Sarah's father, Geoff Houston. "For those who are selling it, if you have any ounce of decency you must stop."